Center post heart valve

ABSTRACT

A prosthetic heart valve has a single center post to guide a movable disc seated on a circular valve ring, that defines an orifice and supports the post. The extremity of the opening movement of the disc is limited by a stop knob attached to the center post. A central recess in the face of the disc engaging the stop hydraulically cushions the stopping of the disc. In another arrangement, the disc is formed with an enlarged central chamber which provides a dampening action of the disc in combination with the post.

Unite States Patent [191 Shiley May 28, 1974.

[ CENTER POST HEART VALVE [76] Inventor: Donald P. Shiley, 11022 Huntinghorn, Santa Ana, Calif. 92705 [22] Filed: Oct. 10, 1972 [21] Appl. N0.: 296,289

[52] U.S. Cl 3/1, 3/DIG. 3, l37/533.23, l37/533.27, l37/533.29

[51] Int. Cl. A6lf 1/22 [58] Field of Search 3/1, DIG. 3; l37/533.l7, 137/533.l9, 533.21, 533.23, 533.27, 533.29

[56] References Cited UNITED STATES PATENTS 6/1953 Moore 137/533.27 X 4/1969 Nakib 6/1969 Jordan 3/1 5/1970 Piene et al. 3/1 8/1970 Cromie 3/1 Primary ExaminerRichard A. Gaudet Assistant Examiner-Ronald L Frinks Attorney, Agent, or Firm-Fowler, Knobbe 8L Martens [57] ABSTRACT A prosthetic heart valve has a single center post to guide a movable disc seated on a circular valve ring, that defines an orifice and supports the post. The extremity of the opening movement of the disc is limited by a stop knob attached to the center post. A central recess in the face of the disc engaging the stop hydraulically cushions the stopping of the disc. In another arrangement, the disc is formed with an enlarged central chamber which provides a dampening action of the disc in combination with the post.

10 Claims, 6 Drawing Figures PATENTEDMYZSIQM 3.812.542

sum 1 or 2 Ill E CENTER POST HEART VALVE BACKGROUND OF THE INVENTION This invention relates to improvements in prosthetic heart valves.

Recent medical history has made the possibility of open heart surgery a reality as a result of the successful development of heart-lung machines. In conjunction with open heart surgery has been the increased successful utilization of artificial heart valves to replace damaged human heart valves. The human heart, being a large muscle, contains certain intake and exhaust cavities through which the blood flows. More commonly, these cavities are referred to as the right and left auricle, and the right and left ventricle. The auricle cavities are the intake cavities of blood from the body and the lungs, while the ventricle cavities are the exhaust cavities of blood to the lungs and the body.

Paramount to the proper flow of blood through the heart and, thus, through the circulatory system, is the functioning of certain primary valves within the heart which monitor the flow of blood. These valves become damaged as the result of disease, age or defects in the development of the heart. The result is an insufficient flow of blood through the system, causing damage or destruction to other vital organs which rely on the adequate supply of blood for survival.

The artificial or prosthetic heart valve offers a remedy to avoid such a catastrophic result. The artificial heart valve is placed within the heart at the position of the damaged human valve, which has been removed, and assumes the function normally performed by the human valve.

However, as with nearly all foreign matter introduced into the human system, there are problems in regard to bodily reaction from or effects on the foreign device. In the case of a heart valve the most prominent problem is in the area of thrombus growth around the artifical valve. Thrombus growth can become quite substantial on areas of low velocity in the flow of blood. The construction of an artificial valve is such that, when it is placed within the heart, it presents certain protrusions into the flow of blood which restrict the natural smooth flow of the blood, causing various low velocity areas susceptible to thrombus growth.

The consequence of thrombus growth around the artiticial valve is a malfunctioning of the valve, for the thrombus will interfere with the proper opening and closing of the valve. The more prominent areas of potential thrombus buildup around the valve are in the vicinity of the valve ring and at the connection of many stationary struts which are used to guide or limit the travel of the valve-element or disc.

An additional detrimental consequence of thrombus growth is the production ofa source of embolus which could cause damage not only within the heart, but also in other vital organs.

Many prior art valve structures comprise configurations utilizing several struts or legs for guiding and limiting the excursion or opening of the valve disc or ball. Each of these legs present a possible area for thrombus growth.

Another significant problem resulting from the use of an artificial heart valve is hemolysis. One of the more prominent sources of this trouble results from the contact between the valve element and the valve body.

Prior art valves are characterized by a significant overlap of these valve elements when seated on the valve body which results in a relatively large contact of surface area giving rise to a substantial occurrence of hemolysis.

A mechanical problem with prior art heart valves has been the wear and/or fatigue of the valve member during its cycling movement between the closed and the open positions. Prior art valves typically utilize a cage or restraining legs to limit the excursion of the valve element. The constant contact between the valve element and the restraining legs eventually deteriorates the valve element as a result of fatigue to the point of possible malfunction of the valve.

An additional mechanical concern of prior art heart valves is the resulting noise caused by the recurring opening and closing of the valve where the valve element contacts the stop means to limit its excursion. This audible noise becomes a source of nuisance and embarrassment to the patient.

SUMMARY OF THE INVENTION The invention presented herein constitutes a valve design to overcome the problems discussed above. This device has a single central post or member to guide the travel of the valve element between the open and closed positions. The use of a single member significantly alleviates not only the problem of thrombus growth, since there is only one strut rather than many, but also the problem of hemolysis, since the precise guidance of the valve element afforded by the central member allows the use of a valve element with a very small overlap when seated on the ring, which also results in lighter weight.

Attached to the central post is a stop means which limits the excursion of the valve element in its open position. In order to reduce the fatigue on the valve element as experienced by many prior art valves, the stop means is designed to be hydraulically received in a recess located on the face of the valve element which contacts the stop means. The recess helps to provide a damper or cushion to the physical contact between the stop means and the valve element.

One embodiment of the invention has a dampening means located within the valve element which performs a double dampening function by cushioning not only the valve element contact with the stop means where the valve is in the extreme open position, but also the valve element contact with the valve body when the valve is in the closed position. Therefore, fatigue is reduced in both the opening and closing movements of the valve element. These and other advantages will be come more evident in the drawings and detailed description below.

THE DRAWINGS FIG. 1 is a perspective view of the preferred embodiment with the single post heart valve in the closed positron;

FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1;

FIG. 3 is a cross-sectional view similar to FIG. 2 except the valve is in the full open position;

FIG. 4 is a perspective view of a second embodiment showing a downstream attachment of the center post to the valve ring;

3 FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. 4; and

FIG. 6 is a cross-sectional view of a third, embodiment of the invention, showing the double dampening element located within the valve element.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, a prosthetic heart valve is shown with a valve body or ring 10, having an inner periphery forming a frusto-conical opening or orifice 14 for fluid flow. The base support structure of the valve body is a frusto-conical retaining ring 16, preferably constructed of a somewhat springy metal. Placed adjacent to the underside of the retaining ring 16 is a cloth pad 18. Extending around and enclosing the retaining ring 16 and cloth pad 18 is a cloth sleeve 20. The combination of the cloth pad 18 and the cloth sleeve 20 forms a circularsuture attachment ring for attaching the prosthetic heart valve to the interior of the heart.

The valve body 10 has an upstream side 22 and a downstream side 24. Extending from the center of the orifice l4 downstream from the valve body 10 is a single stationary member 32 which is attached to the valve body 10. This stationary member 32 is the second leg of a single L-shaped guide member 28 whose first leg 30 extends traversely from the retaining ring 16 in a direction generally parallel with the plane of the valve body to a point 34 on the axis 35 through the center of the orifice 14, but slightly upstream of the orifice 14. The second leg or center guide post 32 extends from point 34 downstream in a direction perpendicular to the general plane of the valve body 10. The L-shaped member 28 is preferably formed by a single piece of wire having a constant diameter of approximately 1/16 inch. Being supported by the retaining ring 16 at only one end, the L-shaped member 28 is attached to ring 16 in cantilever fashion.

Attached to the downstream end 36 of the center post 32 is a stop knob 38 which has greater crosssectional dimension than the cross-sectional dimension of the center post 32.

Slideably mounted on the center post 32 is a valve element 40 of discoidal shape. Through the vertical center of the disc 40 is an opening 42 of a diameter slightly larger than the diameter of the center post 32, so that the disc 40 can easily slide along the stationary center post 32. The disc 40 has an upstream face 44 and a downstream face 46. Located on the center downstream face of disc 40 is a recess 48. The perimeter of the recess 48 is slightly larger than the perimeter 52 of the bottom 54 of the stop knob 38. The depth 56 of the recess 48 is relatively small compared to the overall center thickness of the disc. The cross-sectional shape of the disc 40 reflects a general tapering from a maximum thickness at the center to a minimum or thin thickness at the outer edge 62.

An alternate embodiment of the invention is reflected in FIGS. 4 and 5. The valve body or ring 10' and the valve element or disc 40 are of the same configuration as shown in FIGS. 1 through 3. However, the center guide post 64 is attached to the valve member 10 in a different manner. The center post 64 is the second leg of an angled or somewhat U-shaped guide member 66 which has a curved first leg 68. The curved or generally L-shaped first leg 68 attaches to the downstream side of the retaining ring 16 of valve body 10 and extends in a direction downstream to point 70 on the axis 71 through the center of the orifice l4. Extending from point 70 in a direction along the axis 71, which is perpendicular to the general plane of the valve body 10, to a point 72 just upstream of the center of the orifice 14' is the center post or guide member 64. The U- shaped member 66-, having only one end attached to the retaining ring 16', is a cantilever, since end 72 is not supported. A stop knob 74 is located near the downstream end of the center post 64. The configuration of the center post 64 and stop knob 74 are the same as center post 32 and stop knob 38 of the embodiment of FIGS. 1 through 3.

An additional alternate embodiment is shown in FIG. 6. In this embodiment the valve body 10" is the same as the FIG. 1 valve body 10. Attached to the upstream side 22' of the valve body 10" is a single generally J- shaped guide member 75 with a first leg 76 and a second leg 78. The first leg is attached to the upstream side 22" of valve body 10 and extends to a juncture slightly upstream of the center of the orifice 14". Extending downstream from juncture 80 is the second leg or center guide post 78, which is a guide member. Located at the downstream end of the center post 78 is a stop knob 82 and positioned between the juncture 80 and the stop knob 82 is a damper knob 84. Since the J-shaped member 75 is supported at only one end by its attachment to valve body 10', the J-shaped member 75 represents a cantilever.

Mounted on the center post 78 is a valve element 86 of discoidal shape. Through the vertical center of the disc 86 is an enlarged center hole, recess or core 88 designed to receive the damper knob 84. The disc 86 has an upstream face 90 and a downstream face 92. At the center of the downstream face 92 of the disc 86 is an inwardly extending lip 94 and at the center of the up stream face 90 is an inwardly extending lip 96. The perimeter of the core 88 is slightly larger than the perimeter of the damper knob 84. The opening 98 formed by the lip 94 and the opening 100 formed by the lip 96 are of a size slightly larger than the outside perimeter of the center post 78. The disc 86 is mounted on the center post 78 in such a manner that the damper knob 84 is enclosed within the core 88 by lip 94 and lip 96.

The valve element or disc 86 has cross-sectional shape reflecting a larger disc than that shown in the previously discussed embodiments. The center thickness of the disc 86 must be such that the distance between the downstream face 102 of the lip 94 and the inner surface 104 of lip 96 is approximately the same as or slightly greater than the distance between the upstream side 106 of the damper knob 84 and the upstream side 108 of the stop knob 82. The upstream face 90 and the downstream face 92 of disc 86 taper toward the outer periphery of the disc 86, forming a thinner outer edge 112.

Considering now the operation of these various embodiments of the invention, we first turn to the preferred embodiment shown in FIGS. 1 through 3. For various medical reasons, a significant one of which is a history of rheumatic fever, the human heart valves become damaged and eventually malfunction. Artificial heart valves are used to replace these damaged human valves. In simplified terms, the damaged human heart valve is removed and a prosthetic heart valve is inserted at the same place. In order to attach this man-made heart valve to the interior of the heart, the cloth pad 18 and cloth sleeve 26 are provided to form a suture ring for attachment purposes.

The various cavities of the heart continuously cycle in either contractive or expansive phases. This action produces a pressure in the blood to force it from cavity to cavity and out into the blood system of the body. The artificial heart valve utilizes this systematic recycling process for its operation. The blood flow through the artificial heart valve is through the orifice 14 in a direction generally perpendicular to the plane of the valve body it) and from the upstream side 22 of the valve body it) to the downstream side 24. As shown in FIG. 3 the heart valve is in the open position with the valve element 48 at the downstream end 36 of the center post 32. The blood flows through the orifice l4 and through the opening between the downstream side 24 of the valve body 18 and the outer edge 62 of the disc 40.

The downstream movement or excursion of the disc 40 is limited by the stop knob 38. The stop knob 38 is preferably made of the same metal as the L-shaped member 28. Since the disc 40 is preferably made of a silicone material such as Silastic, as is known in prior art heart valves, the continuous recurring contact between the disc 40 and the stop knob 38 is a source of fatigue to both elements. Also this recycling contact is the source of a clicking noise which is audible once the heart valve is implanted, causing an embarrassing nuisance to the patient. To substantially reduce both of these problems the recess 48 in disc 40 provides a damper or cushion to the contact between the disc 40 and the stop knob 38. As the disc 40 approaches the full open position the stop knob 38 becomes seated within the recess 48 to hydraulically cushion the contact.

The travel of the disc 40 between the closed position of FIGS. 1 and 2 and the opened position of FIG. 3 is guided by a single center guide post 32. The center post 32 runs through the hole 42 in the disc 40. The disc 40 slides along the stationary center post 32 which precisely guides the movement of the disc 40 between its open and closed positions. In the closed position the upstream side 60 of the outer edge 62 of the disc 40 is seated on the downstream side 24 of the valve body 10. The area of contact between the disc 40 and the valve body in this closed position is very small. Since the center post 32 provides precise guidance for the movement of the disc, there is a minimum of overlap by the disc 40 over the orifice l4. Therefore, the disc 40 can be smaller and lighter which aids in the ease of the opening and closing of the valve, because the heavier the valve element 60 the greater the pressure gradient of the blood flow through the heart valve which can be critical to the circulatory system of weaker hearts.

The use of a single L-shaped guide member 28, comprising the center post 32 and the attachment leg 30, provides an important advantage for the implementation of a prosthetic heart valve as shown in the invention. Protrusions into the flow of blood obstruct that flow of blood and cause areas of low velocity where thrombus can develop, causing thromboembolic complications. Prior art valves are characterized by multilegs or multi-struts to guide and limit the movement of the valve element. Using only a single strut or leg significantly reduces the possible areas of thrombus growth. The placement of the L-shaped member 28 as shown in FIGS. 2 and 3 with the attachment leg upstream of the orifice, subjects the single member 28 to a high velocity or high wash area where thrombus growth is less likely.

The cloth sleeve 20 around the valve body 10 is of a loose weave material designed to promote in growth of tissue which will give a smooth tissue surface not susceptible to thrombus growth.

The operation of the alternate prosthetic heart valve shown in FIGS. 4 and 5 is the same as expressed above for the embodiment reflected in FIGS. 1 through 3. However, the difference reflected in this alternate heart valve is the replacement of the single L-shaped member 28 in FIG. 2 with a single angled shaped guide member 66 in FIG. 5. Since the angle shaped member 66 is on the downstream side 24' of the valve body 18, no significant protrusions exist in the flow of blood which may obstruct the flow as it enters the valve.

The additional alternateembodiment shown in FIG. 6 generally operates the same as the embodiment reflected in FIGS. 1 through 3; however, there are some distinguishing features. The most significant difference is the double dampening or cushioning motion of the disc 86. When the disc 86 moves to the fully open position the downstream face 102 of the lip 94 will contact the stop knob 82. This contact will be cushioned by the hydraulic dampened contact between the inner surface 104 of the lip 96 and the damper knob 84.

When the disc 86 moves to the fully closed position the outer edge 112 of the disc 86 contacts the downstream side 24 forming the valve seat of the valve body 10". This contact will likewise be cushioned by the hydraulic dampened contact between the inner surface 105 of the lip 94 and the damper knob 84.

This double dampening effect will greatly reduce fatigue which is usually experienced by the constant recurring contact between the disc and the stop knob, and the disc and the valve body. Also the characteristic clicking" noise produced by the contact between the disc and stop knob is reduced.

An alternate embodiment of the device as shown in FIG. 6 would reflect the center post 78 without the stop knob 82, leaving the damper knob 84 to act as both a stop knob and a damper knob.

What is claimed is:

l. A prosthetic heart valve, comprising:

a valve body for attachment to the heart having an inner periphery defining an orifice for the flow of blood;

a guide member rigidly attached to said valve body and extending from the center of said orifice downstream from said valve body;

a valve element slideably mounted on said guide member which guides the movement of said valve element;

stop means on said member to limit the downstream excursion of said valve element, said stop means having a continuous outer perimeter; and

means for cushioning the contact between said valve element and said stop means said means for cushioning the contact comprising a recess in said valve element shaped to receive the stop means with a close fit.

2. A prosthetic heart valve as specified in claim 1 wherein said recess is in the downstream face of said valve element.

3. A prosthetic heart valve as specified in claim 1 wherein said guide member has an angled shape with two legs, the first leg, forming a support. strut, having one end attached to said downstream side of said valve body and the other end extending to a point downstream on an axis through the center of said orifice and a second leg, forming a center guidev post, extending from saidother end of said first leg along said axis to a point upstream of said orifice.

4. A prosthetic heart valve comprising:

a valve body, having an orifice for fluid flow;

a center guide post attached to said valve body and extending from the center of said orifice to a point downstream of said orifice;

a valve element slideably mounted on said center post; i

a stop knob having'a continuous outer perimeter attached to the downstream end of said center post in order to limit the downstream excursion of said valve element; and

said valve element comprises a generally circular disc having an upstream face and a downstream face, said downstream face having a shallow recess to receive said stop knob in order to dampen the recurring contact between said valve element and said stop knob, the bottom of the recess being closed except to permit said guide post to extend therethrough.

5. A prosthetic heart valve as specified in claim 4 wherein said recess has a perimeter slightly greater than the perimeter of the bottom of said stop means, so that fluid within said recess will act as a cushion to the movement of said stop means in said recess.

6. A prosthetic heart valve comprising:

a valve body, having an orifice for fluid flow;

a center guide post attached to said valve body and extending from the center of said orifice to a point downstream of said orifice;

a valve element slideably mounted on said center post;

a stop knob attached to the downstream end of said center post in order to limit the downstream excursion of said valve element;

said valve element has an enlarged center core through which said post extends, said core having an inwardly extending lip adjacent the upstream face of said valve element and adjacent the downstream face of said valve element, said lips forming openings of a smaller diameter than the diameter of said enlarged center core; and

a damper knob mounted on said post and situated within said core of said valve element, said damper knob being larger than said openings to dampen the opening and closing movement of the valve element.

7. A prosthetic heart valve, comprising:

a generally circular attachment ring covered with suture cloth and whose inner periphery defines an orifice for the flow of fluid;

an L-shaped member with two legs, the first leg being attached to the upstream side of said ring and a second leg extending from the center of said orifice to a point downstream of said orifice in a direction generally perpendicular to the plane of said ring;

a generally circular valve element with its center portion thicker than its edge and slideably mounted on said second leg, said valve element having a center hole of slightly larger diameter than the diameter of said second leg, and said valve element having an outer periphery slightly larger than said inner periphery of said ring; 7

a stop knob located on the downstream extremity of said second leg, so that the excursion of said valve element is limited to the distance between said ring and said stop knob; and

a recess in the center of the downstream surface of said valve element, the perimeter of said recess being slightly larger than the bottom perimeter of said stop knob, so that the said stop knob will rest in said recess when said valve element is at the extremity of its downstream travel.

8. A prosthetic heart valve comprising:

a generally circular attachment ring covered with suture cloth and whose inner periphery defines an orifice for the flow of fluid;

a generally U-shaped member having two legs, a first leg being generally L -shaped having one end attached to the downstream side of said ring and the other end extending downstream to a point corresponding to the center of said orifice and a second leg extending from said other end of said first leg in a direction perpendicular to the plane of said ring to a point upstream of the center of said orifice',

a generally circular valve element with its center portion thicker than its edge and slideably mounted on said second leg, said valve element having a center hole of slightly larger diameter than the diameter of said second leg, and said valve element having an outer periphery slightly larger than said inner periphery of said ring;

a stop knob located on the downstream extremity of said second leg, so that the excursion of said valve element is limited to the distance between said ring and said stop knob; and

a recess in the center of the downstream surface of said valve element, the perimeter of said recess being slightly larger than the bottom perimeter of said stop knob, so that the said stop knob will rest in said recess when said valve element is at the extremity of its downstream travel.

9. A prosthetic heart valve comprising:

a circular attachment ring covered with suture cloth and whose inner periphery defines an orifice for the flow of fluid;

a generally J-shaped member with two legs, the'first leg being attached to the upstream side of said ring and a second leg extending from the center of said orifice to a point downstream of said orifice in a direction perpendicular to the plane of said ring;

a circular valve element with its center portion thicker than its edge and slideably mounted on said second leg, said valve element having an enlarged core at its center and having an inwardly extending lip adjacent the upstream face of said valve element and adjacent the downstream face of said valve element, said lips forming openings of smaller diameter than the diameter of said core; and

a damper knob attached to said second leg at a point between the downstream extremity of said second leg and the center of said orifice, said damper knob being located within said core to dampen the opening and closing movement of said valve element.

10. A prosthetic valve as specified in claim 9, and further comprising a stop knob attached to the downstream extremity of said second leg. 

1. A prosthetic heart valve, comprising: a valve body for attachment to the heart having an inner periphery defining an orifice for the flow of blood; a guide member rigidly attached to said valve body and extending from the center of said orifice downstream from said valve body; a valve element slideably mounted on said guide member which guides the movement of said valve element; stop means on said member to limit the downstream excursion of said valve element, said stop means having a continuous outer perimeter; and means for cushioning the contact between said valve element and said stop means said means for cushioning the contact comprising a recess in said valve element shaped to receive the stop means with a close fit.
 2. A prosthetic heart valve as specified in claim 1 wherein said recess is in the downstream face of said valve element.
 3. A prosthetic heart valve as specified in claim 1 wherein said guide member has an angled shape with two legs, the first leg, forming a support strut, having one end attached to said downstream side of said valve body and the other end extending to a point downstream on an axis through the center of said orifice and a second leg, forming a center guide post, extending from said other end of said first leg along said axis to a point upstream of said orifice.
 4. A prosthetic heart valve comprising: a valve body, having an orifice for fluid flow; a center guide post attached to said valve body and extending from the center of said orifice to a point downstream of said orifice; a valve element slideably mounted on said center post; a stop knob having a continuous outer perimeter attached to the downstream end of said center post in order to limit the downstream excursion of said valve element; and said valve element comprises a generally circular disc having an upstream face and a downstream face, said downstream face having a shallow recess to receive said stop knob in order to dampen the recurring contact between said valve element and said stop knob, the bottom of the recess being closed except to permit said guide post to extend therethrough.
 5. A prosthetic heart valve as specified in claim 4 wherein said recess has a perimeter slightly greater than the perimeter of the bottom of said stop means, so that fluid within said recess will act as a cushion to the movement of said stop means in said recess.
 6. A prosthetic heart valve comprising: a valve body, having an orifice for fluid flow; a center guide post attached to said valve body and extending from the center of said orifice to a point downstream of said orifice; a valve element slideably mounted on said center post; a stop knob attached to the downstream end of said center post in order to limit the downstream excursion of said valve element; said valve element has an enlarged center core through which said post extends, said core having an inwardly extending lip adjacent the upstream face of said valve element and adjacent the downstream face of said valve element, said lips forming openings of a smaller diameter than the diameter of said enlarged center core; and a damper knob mounted on said post and situated within said core of said valve element, said damper knob being larger than said openings to dampen the opening and closing movement of the valve element.
 7. A prosthetic heart valve, comprising: a generally circular attachment ring covered with suture cloth and whose inner periphery defines an orifice for the flow of fluid; an L-shaped member with two legs, the first leg being attached to the upstream side of said ring and a second leg extending from the center of said orifice to a point downstream of sAid orifice in a direction generally perpendicular to the plane of said ring; a generally circular valve element with its center portion thicker than its edge and slideably mounted on said second leg, said valve element having a center hole of slightly larger diameter than the diameter of said second leg, and said valve element having an outer periphery slightly larger than said inner periphery of said ring; a stop knob located on the downstream extremity of said second leg, so that the excursion of said valve element is limited to the distance between said ring and said stop knob; and a recess in the center of the downstream surface of said valve element, the perimeter of said recess being slightly larger than the bottom perimeter of said stop knob, so that the said stop knob will rest in said recess when said valve element is at the extremity of its downstream travel.
 8. A prosthetic heart valve comprising: a generally circular attachment ring covered with suture cloth and whose inner periphery defines an orifice for the flow of fluid; a generally U-shaped member having two legs, a first leg being generally L-shaped having one end attached to the downstream side of said ring and the other end extending downstream to a point corresponding to the center of said orifice and a second leg extending from said other end of said first leg in a direction perpendicular to the plane of said ring to a point upstream of the center of said orifice; a generally circular valve element with its center portion thicker than its edge and slideably mounted on said second leg, said valve element having a center hole of slightly larger diameter than the diameter of said second leg, and said valve element having an outer periphery slightly larger than said inner periphery of said ring; a stop knob located on the downstream extremity of said second leg, so that the excursion of said valve element is limited to the distance between said ring and said stop knob; and a recess in the center of the downstream surface of said valve element, the perimeter of said recess being slightly larger than the bottom perimeter of said stop knob, so that the said stop knob will rest in said recess when said valve element is at the extremity of its downstream travel.
 9. A prosthetic heart valve comprising: a circular attachment ring covered with suture cloth and whose inner periphery defines an orifice for the flow of fluid; a generally J-shaped member with two legs, the first leg being attached to the upstream side of said ring and a second leg extending from the center of said orifice to a point downstream of said orifice in a direction perpendicular to the plane of said ring; a circular valve element with its center portion thicker than its edge and slideably mounted on said second leg, said valve element having an enlarged core at its center and having an inwardly extending lip adjacent the upstream face of said valve element and adjacent the downstream face of said valve element, said lips forming openings of smaller diameter than the diameter of said core; and a damper knob attached to said second leg at a point between the downstream extremity of said second leg and the center of said orifice, said damper knob being located within said core to dampen the opening and closing movement of said valve element.
 10. A prosthetic valve as specified in claim 9, and further comprising a stop knob attached to the downstream extremity of said second leg. 